Relationship between the server parameter file (spfile) in the Oracle 11g parameter file and instance startup

Relationship between the server parameter file (spfile) in the Oracle 11g parameter file and instance startup

When the database starts, it needs to read the parameter file to allocate the memory area and locate the location of the control file. The initialization parameters in the Oracle database are traditionally stored in a text initialization parameter file. for better management, you can choose to use a binary server parameter file to manage the modifications made to the initialization parameter after the database is restarted. the following describes how to use this method to manage initialization parameters.
 
What is a server parameter file?
The server parameter file can be considered as an initial parameter file which is stored in the system running the oracle Database Server. it is designed as a parameter file for server initialization. the initialization parameters stored in the server parameter file take effect permanently. when the instance is running, any changes to the parameters remain valid after the database is restarted. this eliminates the need to manually modify the initialization parameters to make changes to the alter system statement take effect permanently. it also provides the basis for automatic adjustment of database servers.
 
A server parameter file is created by initializing the parameter file from the text using the create spfile statement. (You can also use DBCA to directly create a database ). the server parameter file is a binary file and cannot be modified using a text editor. oracle Database provides other interfaces to view and modify parameters in server parameter files.
 
Note: although you can use a text editor to open a binary server parameter file, you cannot manually modify it. if modified, the file will be damaged. you cannot restart the instance. If the instance is running, it will stop running.

When the startup command without the pfile clause is executed, the oracle instance searches for a server parameter file at a specific default location in the operating system and reads the initialization parameters from the file. if the server parameter file is not found, the instance searches for a text initialization parameter. if the server parameter file exists but you want to use a text initialization parameter to overwrite it, specify the pfile clause when executing the startup command.

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The following is an example:
1. Run the startup command without the pfile clause. The following output shows that the server parameter file spfilejycs. ora is automatically searched at startup.
SQL> startup
ORACLE instance started.

Total System Global Area 630501376 bytes
Fixed Size 2215984 bytes
Variable Size 385880016 bytes
Database Buffers 234881024 bytes
Redo Buffers 7524352 bytes
Database mounted.
Database opened.
SQL> show parameter spfile

NAME TYPE VALUE
-----------------------------------------------------------------------------
Spfile string/u01/app/oracle/11.2.0/db/dbs/
Spfilejycs. ora

 
2. Delete the server parameter file spfilejycs. ora and run the startup command without the pfile clause. The following output shows that
If the server parameter file cannot be found, the system searches for the initjycs. ora text initialization parameter file.
[Oracle @ jyrac1 dbs] $ mv spfilejycs. ora spfilejycs. ora. bak

SQL> startup
ORACLE instance started.

Total System Global Area 630501376 bytes
Fixed Size 2215984 bytes
Variable Size 385880016 bytes
Database Buffers 234881024 bytes
Redo Buffers 7524352 bytes
Database mounted.
Database opened.
SQL> show parameter spfile

NAME TYPE VALUE
-----------------------------------------------------------------------------
Spfile string
 
3. Delete the text initialization parameter file initjycs. ora, and then execute the startup command without the pfile clause. The following output shows that at startup
When the server parameter file is not found, the system searches for the initjycs. ora file, but the text initialization parameter file is deleted.
Initjycs. ora. Therefore, the system prompts that the file cannot be found.
[Oracle @ jyrac1 dbs] $ mv initjycs. ora initjycs. ora. bak

SQL> startup
ORA-01078: failure in processing system parameters
LRM-00109: cocould not open parameter file '/u01/app/oracle/11.2.0/db/dbs/initjycs. ora'
 
4. Run the startup command with the pfile clause. The text initialization parameter file is used to replace the server parameter file. If the spfile parameter value is null, the instance is started using the text initialization parameter.
SQL> startup pfile = '/u01/app/oracle/11.2.0/db/dbs/initjycs. ora'
ORACLE instance started.

Total System Global Area 630501376 bytes
Fixed Size 2215984 bytes
Variable Size 385880016 bytes
Database Buffers 234881024 bytes
Redo Buffers 7524352 bytes
Database mounted.
Database opened.
SQL> show parameter spfile

NAME TYPE VALUE
-----------------------------------------------------------------------------
Spfile string

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